1. Field of the Invention
This invention relates generally to means for controlling and maintaining power output of a broadcast transmitter constant under varying line voltage conditions and more particularly to means for providing power control without affecting modulation percentage while at the same time insuring against overmodulation.
2. Description of the Prior Art
The present invention utilizes pulse width or pulse duration modulation for controlling power wherein a triangular waveform is compared against the audio signal. Pulse width modulators responsive to an input signal for producing an essentially square wave output signal in which the width of the pulses is dependent upon the comparison between a triangular waveform and an audio input are, per se, well known. Such apparatus is taught for example in: U.S. Pat. No. 3,440,566, H. I. Swanson; U.S. Pat. 3,551,851, J. C. Engel; and U.S. Pat. No. 3,585,517, R. B. Herbert.